Daniel Morgan
© Metropolitan Police/PA
Daniel Morgan, a private investigator, was murdered in south London in 1987.
No one has yet been brought to justice.
Rupert Murdoch's media empire could be criticised for its links to the suspects behind the murder of the private detective Daniel Morgan, the Guardian has learned.

The official inquiry investigating his death sent warning letters to people facing criticism in its long-awaited report, which is due to be published on Tuesday. One shows the panel investigating the 1987 killing has been considering describing the defunct News of the World tabloid as being "linked to the criminality associated with the murder". Murdoch's News UK told the Guardian it had not received any letter from the panel warning that it will be criticised, and said it had co-operated with the inquiry, a claim the Morgan family dispute.

Morgan was killed in 1987 in south London, with no one yet brought to justice.

The panel appointed by the government has examined claims that at least two of those arrested in connection with the killing carried out extensive work for the News of the World, which was owned by Murdoch at the time. It has also examined the paper's placing of the lead detective investigating the murder under surveillance. Murdoch closed the Sunday tabloid in 2011 as concerns mounted about its ethics and practices following the phone-hacking scandal.

The murder of Morgan is mired in claims of police and media corruption, and the panel has been investigating the case for the last eight years. Its report will finally be published on Tuesday.

The Met is also bracing itself for censure for being slow in handing to the panel documents that it considered "significant" to its work as it investigated corruption that hampered the murder investigation. More than 20 past or former Met officers, some senior, may face criticism over the case that continues to haunt Britain's biggest police force.

One of the panel's main areas of investigation and findings was the activities of Murdoch's media empire.

The News of the World employed one of the suspects for the murder, paying him £150,000 in a single year after he had become a suspect. It regularly used a private detective agency called Southern Investigations, which Morgan had jointly run with Jonathan Rees. Two executives at the paper set up a business registered at Southern Investigations' address, the Guardian understands.

The panel was considering describing the former Sunday tabloid as being "linked to the criminality associated with the murder of Daniel Morgan", in warning letters sent this year to some of those facing criticism by the panel, and seen by the Guardian.

It is not yet clear whether the criticism about the News of the World and links to criminality, which the panel put in writing in its warning letters, will be included in the final report or if the report will include details of what the alleged criminality consists of.

The panel was examining police corruption that may have shielded the killers. But its terms of reference also state it would examine "the incidence of connections between private investigators, police officers and journalists at the News of the World and other parts of the media and alleged corruption involved in the linkages between them".

News UK, which represents Murdoch's newspaper interests, denied any attempt to influence the government to try to thwart the report.

It insists it did co-operate with the panel, but Raju Bhatt, a solicitor for Alastair Morgan, the brother of the murdered private detective, said:
"Our understanding is that News International did not cooperate with the panel. The failure to co-operate speaks volumes in itself."
News UK, the successor company to News International, said:
"We have cooperated with and assisted the panel during their investigation. No communication has been received from the panel as part of their advance notice of criticism process.

"The suggestion that there has been any attempt by News UK to influence or delay the report's publication is entirely without foundation and false."
Last month the home secretary, Priti Patel, stunned the panel by insisting she must review its report prior to publication, in case it damaged national security or contravened human rights legislation.

The panel had intended for the report, running to more than 1,200 pages, to be published on 24 May. It was at the printers when plans to publish were put on hold. The panel says the Home Office asked for nothing to be blanked out.

The former prime minister Gordon Brown has accused the Murdoch media empire of having links to the "criminal underworld", as part of its techniques to gain sensitive information.

Publication will finally reveal what criticism the panel made, if any, of the pillars of the British power structure, such as the police, Murdoch's media empire and others.

Five police investigations failed to produce a conviction for Morgan's murder and the Met has accepted that corruption in its ranks blighted the search for justice. The panel has also examined whether Freemasonry played any part in the case. Some officers involved in the first investigation were part of the secretive organisation. Rees and other suspects deny involvement in the murder and have won damages for the way the Met pursued the case.

The Morgan case has been described as the real-life version of the hit television drama Line of Duty. The programme's policing adviser worked on the Morgan case while a Met detective in its anti-corruption command.